added str

Author: diptangsu

Sequences.ipynb

@@ -453,10 +453,10 @@
     }
    },
    "source": [
-    "### How do we add all elements from a list to another list?\n",
-    "We use the extend function  \n",
+    "### How do we add all elements from one list to another list?\n",
+    "We use the `extend` function  \n",
     "or  \n",
-    "We add the two lists using +  \n",
+    "We add the two lists using `+`  \n",
     "or  \n",
     "We use list unpacking  "
    ]
@@ -938,7 +938,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 51,
+   "execution_count": 85,
    "metadata": {
     "slideshow": {
      "slide_type": "fragment"
@@ -949,12 +949,12 @@
      "name": "stdout",
      "output_type": "stream",
      "text": [
-      "[100, 9, 8, 7, 6, 5, 4, 3, 2, 1]\n"
+      "[3, 200, 1]\n"
      ]
     }
    ],
    "source": [
-    "x = a[::-1]\n",
+    "x = a[::-1]  # reversing a list\n",
     "print(x)"
    ]
   },
@@ -1249,17 +1249,16 @@
     }
    },
    "source": [
-    "## set\n",
-    "- A list of comma separated values enclosed within curly braces.\n",
-    "- heterogeneous (it can have values of any type)\n",
-    "- mutable\n",
-    "- unordered\n",
-    "- no duplicate elements"
+    "## str\n",
+    "- list of 0 or more characters enclosed within single, double or triple quotes\n",
+    "- immutable\n",
+    "- supports +ve and -ve indexing\n",
+    "- supports slicing"
    ]
   },
   {
    "cell_type": "code",
-   "execution_count": 73,
+   "execution_count": 86,
    "metadata": {
     "slideshow": {
      "slide_type": "subslide"
@@ -1270,38 +1269,50 @@
      "name": "stdout",
      "output_type": "stream",
      "text": [
-      "set()\n"
+      "My name is Diptangsu Goswami\n",
+      "<class 'str'>\n"
      ]
     }
    ],
    "source": [
-    "# Empty set\n",
-    "s = set()\n",
-    "print(s)"
+    "s = 'My name is Diptangsu Goswami'\n",
+    "print(s)\n",
+    "print(type(s))"
    ]
   },
   {
-   "cell_type": "code",
-   "execution_count": 79,
+   "cell_type": "markdown",
    "metadata": {
     "slideshow": {
      "slide_type": "subslide"
     }
    },
+   "source": [
+    "### Length of a str object"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 87,
+   "metadata": {
+    "slideshow": {
+     "slide_type": "fragment"
+    }
+   },
    "outputs": [
     {
      "name": "stdout",
      "output_type": "stream",
      "text": [
-      "{65, 1, 4, 7, 23}\n",
-      "<class 'set'>\n"
+      "My name is Diptangsu Goswami\n",
+      "Length = 28\n"
      ]
     }
    ],
    "source": [
-    "s = {23, 1, 4, 65, 7}\n",
     "print(s)\n",
-    "print(type(s))"
+    "l = len(s)\n",
+    "print('Length =', l) "
    ]
   },
   {
@@ -1312,12 +1323,12 @@
     }
    },
    "source": [
-    "### Adding elements to a set"
+    "### We can use extended slicing to reverse a string"
    ]
   },
   {
    "cell_type": "code",
-   "execution_count": 78,
+   "execution_count": 88,
    "metadata": {
     "slideshow": {
      "slide_type": "fragment"
@@ -1328,45 +1339,109 @@
      "name": "stdout",
      "output_type": "stream",
      "text": [
-      "{32, 1, 2, 4, 10}\n",
-      "{32, 1, 2, 4, 100, 10}\n",
-      "{32, 1, 2, 4, 100, 10}\n"
+      "revrese\n",
+      "eserver\n"
      ]
     }
    ],
    "source": [
-    "s = {2, 4, 32, 1, 10}\n",
-    "print(s)\n",
-    "\n",
-    "s.add(100)\n",
+    "s = 'revrese'\n",
     "print(s)\n",
-    "\n",
-    "s.add(2)\n",
+    "s = s[::-1]\n",
     "print(s)"
    ]
   },
   {
    "cell_type": "markdown",
    "metadata": {
     "slideshow": {
-     "slide_type": "skip"
+     "slide_type": "slide"
     }
    },
    "source": [
-    "***"
+    "### Looping over a string"
    ]
   },
   {
-   "cell_type": "markdown",
+   "cell_type": "code",
+   "execution_count": 89,
    "metadata": {
     "slideshow": {
-     "slide_type": "slide"
+     "slide_type": "fragment"
     }
    },
+   "outputs": [],
    "source": [
-    "## str\n",
-    "- list of 0 or more characters enclosed within single, double or triple quotes\n",
-    "- immutable"
+    "s = 'Loop over me'"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 90,
+   "metadata": {
+    "cell_style": "split",
+    "slideshow": {
+     "slide_type": "fragment"
+    }
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "L\n",
+      "o\n",
+      "o\n",
+      "p\n",
+      " \n",
+      "o\n",
+      "v\n",
+      "e\n",
+      "r\n",
+      " \n",
+      "m\n",
+      "e\n"
+     ]
+    }
+   ],
+   "source": [
+    "l = len(s)\n",
+    "for i in range(l):\n",
+    "    print(s[i])"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 91,
+   "metadata": {
+    "cell_style": "split",
+    "slideshow": {
+     "slide_type": "fragment"
+    }
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "L\n",
+      "o\n",
+      "o\n",
+      "p\n",
+      " \n",
+      "o\n",
+      "v\n",
+      "e\n",
+      "r\n",
+      " \n",
+      "m\n",
+      "e\n"
+     ]
+    }
+   ],
+   "source": [
+    "for ch in s:\n",
+    "    print(ch)"
    ]
   },
   {